In 1796, an English country doctor named Edward Jenner successfully immunized a child against smallpox, the world’s deadliest infectious disease. His experiment, “An Inquiry Into the Causes and Effects of the Variolae Vaccinae” (or “smallpox of the cow”) added the word “vaccination” to our vocabulary. News of Jenner’s stunning achievement led millions throughout Europe to roll up their sleeves. Napoleon, Britain’s mortal enemy, had his troops vaccinated before taking the field. “Ah, Jenner,” he supposedly said after freeing two English prisoners at the doctor’s request, “I can withhold nothing from that man.”

Yet, as Arthur Allen makes clear in “Vaccine,” a timely, fair-minded and crisply written account of “medicine’s greatest lifesaver,” not everyone welcomed Jenner’s feat. Criticism came quickly, often in apocalyptic terms. The economist Thomas Malthus wrote that vaccination might lead to dangerous population increases. Ministers warned against interfering with the Lord’s grand design. Others, meanwhile, objected to a process that injected foreign, perhaps poisonous, matter into the body. What possible good could come from polluting the bloodstream of a child?

For vaccine supporters, the answer was simple. Vaccination saved lives by stimulating the immune system to create protective antibodies against disease. The process wasn’t foolproof, they agreed, and the hazards were real. Vaccines could be contaminated with deadly bacteria; some were too weak to be effective, others so strong they could kill. Yet in a world where millions were dying needlessly from smallpox, this seemed a small price to pay. Vaccination, like other great discoveries, involved risk and reward.

Antivaccine sentiment found fertile soil in the United States, where the ethos of individual responsibility often clashed with public health programs based on collective norms. As Allen notes, Americans remained suspicious of calls for mandatory vaccination. Indeed, one of the potent symbols of the early antivaccine movement was the limp “Raggedy Ann” doll, created in 1915 by a man whose daughter had died shortly after being vaccinated at school without parental consent. Authorities blamed a heart defect; her parents blamed the shot.

What kept vaccine opponents on the defensive, however, were the rapid breakthroughs in medicine and public health. Jenner’s triumph was followed by a procession of other vaccines, for rabies, tetanus, yellow fever, diphtheria and more. A healthier diet, advances in sanitation and surgery, the development of antibiotics and DDT — all combined to increase the average American life expectancy to 70 years from 47 between 1900 and 1955.

Allen sees two events in these years as crucial to the growing public acceptance of vaccines. When America went to war in 1941 following Pearl Harbor, the health of the troops became a primary concern. Determined to prevent the medical casualties of World War I, where the number of American soldiers killed by influenza (44,000) almost matched the number lost in battle (50,000), military officials made vaccination mandatory. “Yes, the shots hurt and even caused illness sometimes, but the soldier survived,” Allen writes. “Returning from the war he wanted his children to have the same protection.”

World War II made vaccination fashionable. Polio turned it into a national crusade. No disease drew as much attention in postwar America, or created as much fear. Primarily striking children, polio killed some of its victims and paralyzed others, leaving behind vivid reminders for all to see: wheelchairs, leg braces, iron lungs, deformed limbs. The quest for a means of prevention led to the largest public health experiment in American history, involving nearly two million school-age volunteers. When Jonas Salk’s killed-virus polio vaccine was declared “safe, effective and potent” in 1955, the nation celebrated as if a war had ended — and, indeed, one had. At a White House ceremony, President Eisenhower choked back tears as he told the young researcher: “I have no words to thank you. I am very, very happy.”

The polio vaccines of Salk and Albert Sabin marked a special moment in medical history. As late as the 1950s, parents had been encouraged to expose their children to diseases like measles, mumps and chicken pox in order to get them over with before adulthood, when the dangers increased. Now, there were vaccines for all these illnesses, and more were on the way. Some researchers spoke openly of a future without infectious disease. “Will such a world exist?” a scientist asked. “We believe so.”

In our current age of AIDS, Ebola and avian flu, one marvels at the arrogance of these words. Nature remains a full step ahead. For Allen, growing fears of vaccination in the decades after Salk’s triumph are partly a function of these heightened expectations. But more important, he thinks, was the general fallout from catastrophes like Watergate and Vietnam, which undermined institutional authority across the board. By 1980, the days of deferring to the expertise of doctors and researchers, pharmaceutical companies and federal bureaucrats, were long gone in the United States — and unlikely to return. The public’s portrait of a medical researcher had turned from the selfless and independent Salk working on behalf of children to that of a lab-coated lackey from a drug giant conspiring to hide the dangers of products that are slickly marketed and wildly overpriced.

In terms of vaccination, the Watergate moment occurred in 1982, when a television station in Washington, D.C., broadcast an ominous documentary about the dangers of D.T.P., a standard childhood shot for diphtheria, tetanus and pertussis (whooping cough). Titled “Vaccine Roulette,” it was, Allen notes, a story “waiting to be told.” The pertussis component had proved extremely effective against a wretched, life-threatening disease. But side effects, including convulsions and brain damage, were reported in a tiny percentage of those who received it. By playing up the perils of D.T.P., while minimizing the seriousness of pertussis, the documentary ignited a grass-roots movement of alarmed parents — some suspecting that their children had been damaged by D.T.P., others concerned by the ever growing number of vaccines being recommended by their pediatricians. For Allen, this was a signal opportunity — a chance to educate the public about the process of vaccination. But little positive came of it, beyond a national compensation program in 1986 that allowed families claiming vaccine-injury to file for government payments.

Allen is sympathetic to parental fears regarding the dangers of various vaccines, though he remains skeptical that scientific studies of these dangers, no matter how rigorous, will open many minds. At this point, he writes, much of the “antivaccinist” leadership is composed of countercultural types who view life through the prism of conspiracy theory: the government lies, the drug companies are evil, the medical profession is corrupt; trust the Internet instead. A fair number oppose traditional medicine in favor of homeopathy, believing that vaccines weaken the immune system and that sickness is a natural part of life. “We treat our children like machines that are never supposed to slow down or let us miss a day of work,” a mother told Allen. “We never allow them the soulfulness of being ill.”

To a large extent, says Allen, this antivaccination impulse is fueled by an ignorance of the past. Vaccines have done their job so well that most parents today are blissfully unaware of the diseases their children are being inoculated against. The end result is a culture that has become increasingly risk-averse regarding vaccination because people have greater trouble grasping the reward.

The problem appears to be growing. As more children go unvaccinated in the United States, there has been a rise in vaccine-preventable diseases. Meanwhile, fewer pharmaceutical companies are now producing vaccines, citing the high cost of testing, diminishing markets and a fear of litigation. For Allen, a reversal of these trends will require something long overdue: a frank national discussion about the risks and benefits of vaccination. His splendid book is a smart place to begin.

David Oshinsky holds the Jack S. Blanton chair in history at the University of Texas at Austin. His most recent book, “Polio: An American Story,” won the Pulitzer Prize for history.